DEVELOPMENTAL-CHANGES IN METHYLATION OF SPERMATOGENESIS-SPECIFIC GENES INCLUDE REPROGRAMMING IN THE EPIDIDYMIS

We have determined the status of DNA methylation at specific sites in three spermatogenesis-specific genes, Pgk-2, ApoA1 and Oct-3/4, throug hout the development and differentiation of male germ cells in the mou se. We observed a specific demethylation event in the Pgk-2 gene in pr ospermatogonia at about the time of birth, about 10 days before the on set of transcription which first occurs in primary spermatocytes. All three genes were unmethylated in adult spermatogenic cells in the test is, but were remethylated in mature spermatozoa in the vas deferens. S urprisingly, we found that this remethylation is part of the process o f sperm maturation which occurs in the epididymis.